1. Technical Field
The present disclosure relates to a technique of disposing an electronic control unit above a transaxle via a plurality of support brackets.
2. Description of Related Art
There is known a mounting structure in which (i) an electronic control unit has a plurality of support brackets that are provided so as to be spaced apart from each other in a longitudinal direction of a vehicle and to protrude downward, and (ii) the electronic control unit is attached to a transaxle case in a state of floating above the transaxle case via the plurality of support brackets. The structure described in Japanese Patent Application Publication No. 2014-168356 (JP 2014-168356 A) is its one example in which a power control unit (PCU) including an inverter and so on, as an electronic control unit, is disposed above a transaxle for a hybrid vehicle including an electric motor for use as a travel driving force source and is attached to the transaxle via a plurality of support brackets.
In the meantime, in such a mounting structure, when, for example, the rear-side support bracket, on the rear side of the vehicle, of the plurality of support brackets described above is provided at a position spaced from the transaxle case toward the rear side of the vehicle, it may be considered that (iii) an intermediate bracket protruding from the transaxle case toward the rear side of the vehicle is integrally fixed to a flat mounting surface at a rear end of an upper surface of the transaxle case, and that (iv) the rear-side support bracket is fixed to a protruding portion of the intermediate bracket (unknown). In this case, for example, any one of a plurality of kinds of electronic control units with different sizes per type of vehicle can be attached to a transaxle case that is commonly used regardless of the type of vehicle.
However, in the case where the rear-side support bracket is fixed at the position spaced from the transaxle case toward the rear side of the vehicle as described above, when a collision load toward the rear side of the vehicle is applied to the electronic control unit at the time of vehicle collision, a moment is generated by a load that is applied from the rear-side support bracket to the intermediate bracket, so that there is a possibility that a load in a lifting direction may act on a fixed portion of the intermediate bracket to the transaxle case, resulting in a decrease in fixing strength. When the fixing strength is decreased, the intermediate bracket along with the electronic control unit may come off the transaxle case, or the transaxle case may be subjected to failure due to the dislocation of the intermediate bracket.
For example, as shown in FIG. 9, in the case where a flat-plate intermediate bracket 100 is fixed to a mounting surface 42 of a transaxle case 22 by a bolt 44 and where a rear-side support bracket 16 of an electronic control unit 20 is fixed to a protruding portion, protruding from the transaxle case 22 toward the rear side of the vehicle, of the intermediate bracket 100, a moment MA may be generated about a rear-side upper-end corner S, as a fulcrum, of the transaxle case 22 at the time of vehicle collision, so that a lifting load Fzb may act on a fastened portion by the bolt 44 due to the moment MA. Then, when such a lifting load Fzb acts thereon, a frictional force Fxa decreases correspondingly, and therefore, the intermediate bracket 100 may be dislocated toward the rear side of the vehicle due to a rearward load Fxb as shown by an arrow A in FIG. 10 to thereby cause the bolt 44 to tilt as shown by an arrow B, so that a crack or the like may occur starting from an opening portion of a threaded hole 54 due to prying or the like of the bolt 44 to thereby cause failure of the transaxle case 22.